Vacuum valves are used in systems requiring control of a source vacuum to outlet ports. In automotive climate control systems, the vacuum valves are typically an assembly that achieves valve operation by sliding or rotating a channeled pliable selector plate, usually made of a rubber material, over a rigid ported stator made of plastic or die-cast metal to provide the routing of the source vacuum.
The problems associated with such vacuum valves are as follows: 1) The sliding or rotating of the rubber selector plate on the stator typically has a frictional force associated with the motion. 2) There is usually a tolerance stack-up from the parts, as well as the material composition that can sometimes produce a borderline seal condition. 3) The associated break-away torque or force to operate the switch is usually temperature dependent. 4) The leak rate of the assembly is dependent on the clamping force of the components which can increase the frictional force. This is an undesirable condition, for it inhibits smooth operation of the valve.